Bugfix about pickle translator & LodelContext

The is_instance test on classes loaded from a pickle file is not
relevant :
lodel.editorial_model.components.EmClass != lodelsites.__loader__.editorial_model.components.EmClass

lodel/editorial_model/components.py

             m.update(bytes(data, 'utf-8'))
         return int.from_bytes(m.digest(), byteorder='big')
 
+    ##@brief Type test method
+    #@return bool
+    #@note Those methodes are implemented because we use picklefile to store
+    #EM -> the classes that are stored are not the same than the one loaded
+    #by LodelContext : lodel.editorial_model.components.EmClass !=
+    #lodelsites.INSTANCE_NAME.editorial_model.components.EmClass
+    @classmethod
+    def is_emclass(cls):
+        return False
+
+    ##@brief Type test method
+    #@return bool
+    @classmethod
+    def is_emgroup(cls):
+        return False
+
+    ##@brief Type test method
+    #@return bool
+    @classmethod
+    def is_emfield(cls):
+        return False
 
 # @brief Handles editorial model objects classes
 #@ingroup lodel2_em
                 data_handler='LeobjectSubclassIdentifier',
                 internal=True,
                 group=group)
+    
+    ##@todo delete me when support for pickle translator is dropped
+    @classmethod
+    def is_emclass(cls):
+        return True
 
     # @brief Property that represent a dict of all fields (the EmField defined in this class and all its parents)
     # @todo use Settings.editorialmodel.groups to determine wich fields should be returned
         else:
             group.add_components([self])
 
+    ##@todo delete me when support for pickle translator is dropped
+    @classmethod
+    def is_emfield(cls):
+        return True
+
     # @brief Returns data_handler_name attribute
     def get_data_handler_name(self):
         return copy.copy(self.data_handler_name)
                     raise ValueError("EmGroup expected in depends argument but %s found" % grp)
                 self.add_dependencie(grp)
 
+    ##@todo delete me when support for pickle translator is dropped
+    @classmethod
+    def is_emgroup(cls):
+        return True
+
     # @brief Returns EmGroup dependencie
     # @param recursive bool : if True return all dependencies and their dependencies
     # @return a dict of EmGroup identified by uid

lodel/editorial_model/model.py

                 logger.debug("Set group '%s' as active" % agrp)
                 grp = self.__groups[agrp]
                 self.__active_groups[grp.uid] = grp
-                for acls in [cls for cls in grp.components() if isinstance(cls, EmClass)]:
+                for acls in [cls for cls in grp.components() if cls.is_emclass()]:
                     self.__active_classes[acls.uid] = acls
             if len(self.__active_groups) == 0:
                 raise RuntimeError("No groups activated, abording...")